This NEI planning grant proposal supports the development and refinement of procedures for a multi-center clinical trial that will be designed to compare the benefits and costs of two currently accepted treatment approaches for patients with convergence insufficiency (CI). CI is a very common and distinct binocular vision disorder. It affects approximately 5 percent of children and adults in the United States, and it may have a serious impact on an individual's performance in school, choice of jobs, and quality of life. Clinical signs of CI include exophoria that is greater at near than at far, a receded near point of convergence, and reduced positive fusional vergence. Common symptoms include double vision, eyestrain, headaches, and blurred vision while reading. There is no consensus regarding the most effective treatment for CI. The two most common treatments are "pencil push-ups" and vision therapy/orthoptics. Significant differences exist between the two procedures in cost and number of visits required, with pencil push-ups the less expensive alternative. A prospective, masked, controlled study is needed to determine the relative benefits and costs of these widely accepted treatments. In the proposed study, Convergence Insufficiency Treatment Trial (CITT), patients between the ages of 9 and 30 years will be randomly assigned to: 1) home-based pencil push-up treatment, or 2) office-based vision therapy. Measurements of the signs and symptoms of CI will be made by masked examiners at baseline, during the 12-week treatment phase, and after 12-months of follow-up. The primary outcome variable will be the number of patients classified into treatment categories "success," "improvement," or "failure," based on the level of improvement in the signs (near point of convergence and positive fusional vergence) and symptoms. Significant preliminary work needs to be performed before undertaking this multi-center clinical trial. The planning grant award will allow the CITT Study Group to conduct pilot studies to demonstrate recruitment potential, assess adherence with treatments, determine sample size, refine categories and measures for eligibility and outcomes, and develop the manual of procedures.